I was eating out with a group of friends recently and we were all ordering cocktails when it came up that one member of our party (a friend of friend who we'd just met that night) was an alcoholic. Well, that sure put a damper on the party fast. I felt so awkward drinking in front of him and I know my friends did too because none of us ordered another one (which we usually always do). What should we have done? Was it rude to drink in front of this man?
You are not in charge of this man's sobriety, he is. If he feels comfortable going to a restaurant that serves alcohol, then I think you can assume that he has a handle on his addiction and can watch other people drinking without putting himself at risk. Recovering alcoholics (hopefully) have learned tools to help them manage their disease and function in everyday life. Perhaps someone asked him why he wasn't ordering a drink? I'm guessing that he wouldn't have bothered to bring it up unless there was a reason.
In fact, it sounds like you might have made it more awkward by making it into a big deal. Rule of thumb here: trust people to know what's best for them. If you're unsure in the future, you could always just casually say something like, "are you comfortable if I order a drink?" and go from there.